The present invention relates to a method and a device for wrapping a product in a wrapper of sheet material. The invention has been developed with particular attention to its possible use for packaging products such as, for example, food products, particularly confectionery. In this field of application, the products (for example, spherical pralines, hollow or filled chocolate eggs, etc.) are quite often wrapped in sheets of material such as, for example, aluminium.
For example, European patent EP-B-0 082 952 describes a method which enables an approximately spherical praline to be wrapped in a sheet of aluminium. For this purpose, the product, placed on a sheet of aluminium, is passed through a structure with resilient blades so that after the sheet has assumed a generally cup-like configuration, as a result of being wrapped around the product, it is closed behind the product like a bunch or tail when the latter emerges from the resilient formations. The bunch or tail thus formed is then upset onto the product so that the product is completely wrapped in the sheet.
A solution which achieves the same final effect by a slightly different method is described in German patent DE-A-32 43 500.
The solutions described in the prior documents mentioned above produce excellent results, particularly as regards the appearance of the final product obtained. This is usually intended to be inserted in a paper cup with pleated walls with the portion of the wrapper which is upset onto the product facing downwardly, resting on the base of the cup. The upper part of the product is thus protected by a sheet wrapped neatly around the product.
The Applicant has found that these previously known solutions could be further improved, particularly as regards isolation from the outside atmosphere.
From this point of view, it is generally known (see, for example, German utility model DE 1784647U) to package food products (such as chocolate or sugar-based products) in close-fitting wrappers of sheet material, such as aluminium, which are produced by forming two complementary aluminium leaves, each of which closely copies the shape of a respective half of the product. The two leaves of sheet wrapper thus produced are then interconnected along an equatorial line of the product, for example, by heat sealing, making use of the presence of a coating of hot-melting material on the mutually coupled faces, with the removal of the remaining parts of aluminium sheet which project beyond the region of the seal.
This solution, however, is unsuitable for use in a field such as that described above, particularly when the wrapped product is to be inserted in a paper cup. In fact the seal along the equatorial line is visible, giving the product as a whole an appearance typical of an automatically-packaged industrial product. On the other hand, it is desirable, particularly in the confectionery field, for the industrial product to retain presentation characteristics typical of a hand-made or semi-hand-made product and hence not to display seal lines, which are signs of the intervention of a machine, in visible positions.